Crankshaft phasing mechanism

Abstract

A variable compression ratio engine has a pair of crankshafts connected by a phase adjuster mechanism operative to change the phase angle between the crankshafts so as to vary the compression ratio of the engine. The phase adjuster mechanism includes two pairs of helical phasing gears. Each of those pairs consists of a gear fixedly mounted on a crankshaft and, operatively engaged therewith, a wider gear fixedly mounted on an axially movable adjuster member. The crankshafts can be arranged in-line or side-by-side in parallel. Each of the phasing gears which is fixedly connected to the axially movable adjuster member is bounded by a respective imaginary cylindrical surface whose axis coincides with and whose points are equidistant from the axis of rotation of the adjuster member, and whose diameter is equal to the outside diameter of that phasing gear, and which extends along the length of the engine block without intersecting the envelope swept by each crankshaft and connecting rod means associated with that crankshaft whereby the phasing gears of the phase adjuster mechanism are operable along the shole length of the engine block so as to minimize the length of each of the crankshafts and, ultimately, the external lengthwise dimensions of the engine.

What is claimed is: 
     
       1. In a VCR engine having two crankshafts which rotate about parallel axes, one or more pairs of pistons with one piston in each pair linked to one of the crankshafts and the other piston in each pair linked to the other crankshaft, the pistons in each pair operating in interconnected cylinders, a phase adjuster mechanism including an axially movable adjuster member and two pairs of helical phasing gears, said member rotatable about an axis parallel to the axes of rotation of the crankshafts and supported by radial sliding bearings, each pair of said phasing gears consisting of a phasing gear fixedly mounted on a respective one of said crankshafts and a respective wider phasing gear operatively engaged therewith and fixedly mounted on the adjuster member, the respective helix angles and directions of helices of said phasing gears being arranged to alter the phase relation between the two crankshafts in response to axial displacement of the adjuster member, the combination comprising: an engine block;   connecting rod means operatively associated with the crankshafts;   each of said crankshafts together with the connecting rod means associated therewith sweeping a respective envelope during engine operation;   each of said two phasing gears on said adjuster member bounded by a respective imaginary cylindrical surface whose axis coincides with and whose points are equidistant from the axis of rotation of said adjuster member, and whose diameter is equal to the outside diameter of said phasing gear bounded thereby and which extends axially along the length of said engine block without intersecting said envelopes.   
     
     
       2. In the VCR engine of claim 1, said radial sliding bearings having bearing journals incorporated on said axially movable adjuster member;   at least one said bearing journal located adjacent to a phasing gear fixedly mounted on said adjuster member;   each said bearing journal that is located adjacent to a phasing gear fixedly mounted on said axially movable adjuster member has a diameter greater than the outside diameter of that phasing gear.   
     
     
       3. In the VCR engine of claim 2, means defining a mating bearing surface for each said bearing journal located adjacent to a phasing gear fixedly mounted on said axially movable adjuster member,   each said bearing journal being shorter than its mating bearing surface.   
     
     
       4. In the VCR engine of claim 1, a stationary shaft;   and said radial sliding bearings having bearing journals incorporated on said stationary shaft.   
     
     
       5. In the VCR engine of claim 1 a stationary shaft,   and said radial sliding bearings consisting of at least one bearing having a bearing journal incorporated on said axially movable adjuster member and at least one bearing having a bearing journal incorporated on said stationary shaft.   
     
     
       6. In the VCR engine of claim 5, at least one said bearing journal on said axially movable adjuster member being located adjacent to a phasing gear fixedly mounted on said adjuster member;   each said bearing journal that is incorporated on said axially movable adjuster member and located adjacent to a phasing gear fixedly mounted on said adjuster member has a diameter greater than the outside diameter of that phasing gear.   
     
     
       7. In the VCR engine of claim 6, means defining a mating bearing surface for each said bearing journal incorporated on said axially movable adjuster member and located adjacent to a phasing gear fixedly mounted on said adjuster member;   each said bearing journal being shorter than its mating bearing surface.